求前k个最小的数---类似快排思想的O（n）

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#include<iostream>#include<vector>#include<algorithm>using namespace std;int Partition(vector<int>&data,int headId,int tailId){int posSlow = headId-1,posFast=headId;for(;posFast<tailId;++posFast){if(data[posFast]<data[tailId]){++posSlow;swap(data[posSlow],data[posFast]);}}++posSlow;swap(data[posSlow],data[tailId]);return posSlow;}void FindKLeast(vector<int>&data,int headId,int tailId,int k){if(headId<tailId){int midId=Partition(data,headId,tailId);if(midId>k){FindKLeast(data,headId,midId-1,k);}else{if(midId<k){FindKLeast(data,midId+1,tailId,k);}}}}void FindKLeastNumbers(vector<int>&data,unsigned int k){int len = data.size();if(k>len){throw new std::exception("Invalid argument!");}FindKLeast(data,0,len-1,k);}int main(){int a[]={12,42,10,31,6,15};int k=3;vector<int>::iterator iter;vector<int> ivector(a,a+6);FindKLeastNumbers(ivector,k);cout<<"前k个最小的数为："<<endl;for(iter = ivector.begin();iter<=ivector.begin()+k-1;iter++)cout<<*iter<<"  ";cout<<endl;}

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